Along with scaling of semiconductor devices, various light exposure techniques for forming fine patterns have been proposed. For example, there is known a light exposure apparatus (which will be referred to as an EUV light exposure apparatus, hereinafter) using extreme ultraviolet rays having a wavelength of about 100 nm or less (Extreme Ultraviolet Light: which will be referred to as EUV light, hereinafter). Further, other than this, there is also known a technique for forming fine patterns by combining an ArF immersion exposure tool with Dual Tone Development (which will be referred to as DTD, hereinafter).
The DTD is a technique that performs positive development and negative development. In the positive development, resist portions irradiated with light exposure energy of a certain level or more are dissolved by a development process. In the negative development, resist portions irradiated with light exposure energy of a certain level or less are dissolved by a development process. The certain level of the negative development differs from that of the positive development. With this technique, the pitch of periodic patterns is reduced to a half.
When the DTD is used, the pitch of periodic patterns can be reduced, but isolated patterns end up being processed such that only the outer peripheral portions of the isolated patterns are left. Accordingly, the DTD cannot be utilized to form isolated patterns.